1. Field of the Invention
The present invention relates generally to a cleaning method and equipment for dipping an object to be treated, such as a semiconductor wafer or a glass substrate for a LCD, into a cleaning solution, such as a chemical or pure water, to clean the object.
2. Related Background Art
In a typical production process for a semiconductor equipment, there is widely adopted a cleaning equipment for sequentially dipping objects to be treated, such as semiconductor wafers or glasses for LCDs, (which will be hereinafter referred to as "wafers"), into a cleaning solution, e.g., a chemical, such as aqueous ammonia (NH.sub.4 OH) or hydrofluoric acid (HF), and/or a rinsing solution (pure water), which are stored in a cleaning bath, to clean the objects.
As a conventional cleaning equipment of this type, there is widely used a cleaning equipment wherein a cleaning bath for storing therein a cleaning solution to dip objects to be treated into the cleaning solution to clean the surfaces thereof is connected to a pure water supply source by means of a cleaning solution supply pipe which is connected to a chemical storing container for storing therein a chemical, the chemical in the chemical storing container being pressurized by an inert carrier gas, such as nitrogen (N.sub.2), to be injected into pure water flowing through the cleaning solution supply line so that a predetermined concentration of chemical is supplied to the cleaning bath to clean the objects.
However, in the conventional cleaning equipment of this type, since the chemical stored in the chemical storing container is pressurized by the inert gas, such as N.sub.2 gas, to be injected into the pure water line, the injection speed of the chemical injected into the pure water line is set to be constant, so that there is a problem in that it is difficult to change the injection speed within a short time.
Therefore, there are problems in that it is not possible to quickly and appropriately control the injection speed of the chemical in order to obtain an appropriate concentration of cleaning solution corresponding to the conditions of the objects to be treated, and it is not possible to sufficiently supply the appropriate concentration of cleaning solution corresponding to the conditions of the objects to be treated, so that cleaning efficiency and yields deteriorate.